Clock system.



jgg A9 A.F.PO0LL CLOCK SYSTEM.

ABPLICATION FILED OCT. 24. I917.

1,3 1 0,375. Patented July 15, 1919.

ARTHUR I. POOLE, OF CHICAGO, ILLINOIS.

CLOCK SYSTEM.

Specification of Letters Patent.

Patented July 15, 1919.

Application filed October 24, 1917. Serial No. 198,332.

To all whom it may concern:

Be it known that I, ARTHUR F. Poona, a citizen of the United States, andresident of Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Clock Systems, of whichthe following is a specification.

My invention is an electric clock system and has for its object theimprovement of systems of the prior art in which a master clock controlsa plurality of secondary clocks through the agency of currents made orbroken at certain predetermined intervals.

My improved system will be best under stood by reference to theaccompanying figures, of which- Figure 1 is a diagrammatic view of thepreferred embodiment of my system, and

Fig. 2 is a circuit modification thereof.

Referring particularly to Fig. 1, 1 is a master clock, which may be ofany suitable construction, although I prefer to use a clock which iselectrically wound. The master clock 1 is controlled by a pendulum 2,which is driven by a pair of pallets 3, driven by an escape wheel 4,fnounted on a shaft 5. The relation of the length of the pendulum andthe teeth of the escape wheel 4 is such that the shaft makes onerevolution per minute, and on said shaft is mounted circuit closingmechanism hereinafter to be described. The time between the operationsof the circuit closing! mechanism is one minute, although any otherinterval of time may be used, such, for instance, as one-fourth of aminute, or even a period as long as fifteen minutes. In this latterevent, the contact-making machanism hereinafter to be described wouldnot be placed upon the escape wheel shaft 5, but upon some other portionof the clock mechanism.

The pallet 3 is supported on a shaft 6, which is connected by the usualcrutch 7 to the pendulum. On the pallet shaft 6 and insulated from it isa spring arm 8, which is adapted to make contact with an arm 9, mountedon the escape wheel shaft 5 and rotating with it. Contact of the arms 8and 9 will occur once for each revolution of the escape wheel shaft 5,and consequently in the specific structure herein described will occuronce each minute. A suitable source of current, such for instance as abattery 10, is provided and the arms 8 and 9 are in an electric circuitas shown, said circuit including a relay 11, which is provided for thepurpose of controlling the current sent out over the clock system.

From what has been described, it is obvious that the relay 11 will beenergized once each minute. I will now describe the means by which thesecondary clocks are driven and held in synchronism with the operationsof the relay 11.

The secondary clocks are connected in parallel to the line wires and theline wires are supplied from the source of alternating current, such forinstance as the ordinary current used for electric lighting purposes.

The secondary clocks each contain a small induction motor, whcih mayadvantageously be of the type used in induction watt meters, that is, aform in which a conducting disk is rotatably mounted in a shiftingmagnetic field. In the preferred embodiment of my invention shown, Ihave secured this shifting magnetic field by the well-known expedient ofhaving an electromagnet with shaded poles. The secondary clocks containin them mechanism to regulate the speed of rotation of the conductingdisk and this mechanism is governed through the momentary breaks in thecircuit which supply the induction motor with power.

To recapitulate, the general scheme of my clock system is to provide aseries of secondary clocks driven by suitable continuously runningmotors and to synchronize these motors at periodic intervals withcurrents from a master clock. Synchronism is not attained by suddenlyshifting the motors or the parts driven therefrom the amount of theerror existing at the time the synchronizing current is sent out, but isaccomplished by changing the speed governing means of the motor, so thatthe motor will run faster or slower in order to bring the parts movedthereby into synchronism. I will now describe the specific mechanism ofthe secondary clock.

The mechanism is shown in diagrammatic form only, since the partsconstituting the secondary clocks are all so well known that a merelydiagrammatic illustration of them will be sufiicient to inform thoseskilled in the art of the preferred means of practising my hereindescribed invention. The motive power of the secondary clocks isprovided by a conducting disk 12, which is arranged to rotate betweenthe shaded poles of an electromagnet 13, which is connected between theline wiresl-l and 15. As before noted, these line wires are supplied byan alternating electric current from the mains 16 and 1'7. The relay 11is provided with an armature 18, which is held by a spring 19 against acontact point 20, thereby maintaining a cur: rent supply on the linewires 14 and 15. Once each minute when the arm 8 makes contact with thearm 9, the armature 18 is attracted momentarily and this breaks thecurrent on the line wires 14 and 15. However, the momentum of the disk12 is suflicient to maintain it in rotation during the period of deinergization of the magnet 13. The magnet 13 is provided with anadjustable magnetic shunt 21, which is provided with a screw arrangement22, so that its distance from the poles of the electromagnet 13 may bechanged. Obviously if the shunt 21 is approached to the poles of themagnet 18, the effective torque upon the disk 12 will be diminished andits speed will be accordingly decreased. The contrary will be true ifthe shunt 21 is withdrawn from the poles of the electromagnet 13.

I shall now describe the means for bringing the rate of rotation of thedisk 12 into synchronism with the breaks in the supply current caused bythe relay 11. The disk 7 12 is mounted upon a shaft 23, which isprovided with a worm 24, which drives a gear 25 on a shaft 26, providedwith a worm 27 driving a gear 28 on a shaft 29, which by suitablegearing 30 drives the hands 31 of a secondary clock. The arrangementjust described may be taken as typical of any of the secondary clocksconnected with the circuit. The disk 12 is so geared to the shaft 29that when said disk is running at its normal rate, the time of onerevolution of the shaft 29 is just equal to the interval betweensuccessive breaks of the supply current caused by the electromagnet 11.For instance, if the master clock 1 opened the line circuit once eachminute, the shaft 29 would revolve once each minute also.

Mounted on the shaft 29 are two segmental gears 32 and 33, which eachhave slightly over half of their teeth cut away, as will be clearlyshown by reference to Fig. 1. The shaft 29 and its rigidly attachedgears 32 and 33 turns'in the direction of the arrow shown on thesegmental gear 33. The segmental gears 32 and 33 are for the purpose ofmoving the magnetic shunt 2-1 as may be required and to this end I haveprovided a shaft 34, on which is rotata'bly mounted a gear 35, and alsoan arm 36 having rotatably mounted thereon .two spur gears 37 and 38.The spur gear 38 is adapted to be engaged by the teeth of the segmentalgear 33 and not by the teeth of the segmental gear 32. The spur gear 37meshes in both the spur gear 38 and the gear 35, and is adapted to beengaged by the teeth of the segmental gear 32, but not by the teeth ofthe segmental gear 33. The arm 36 is normally held so that the spurgears 37 and 38 are out of mesh with the gears 32 and 33, by means of alatch 39 having two armatures 40 and 41 rigidly attached thereto andurged against a stop 43 by a rctractile spring The armature 40 isadapted to be attracted by an electromagnet 45, and the armature 41 tobe attracted by an electromagnet 46. The electromagnet 45 is connectedin a shunt circuit around the electromaguet 46 and said shunt circuitincludes a condenser 47 therein, or other equivalent means of splittingthe phase. The electromagnets 45 and 46 are connected to the line wires14 and 15.

Rigid with the gear 35 is a bevel gear 48 engaging a =bevel 49 on ashaft 50, on which is the screw 22 previously referred to. The arm 36has a tail 51 rigidly attached thereto, and said tail is adapted to beengaged by a series of cams 52, 53 and 54 on the shaft 29. It will thusbe seen that if the arm 36 is dropped, allowing the gears 37 and 38 tocome in position to mesh with their coiipcrating segmental gears 32 and33 that rota tion of the shaft 29 will revolve the shaft 50 first in onedirection and then in the reverse direction, thereby raising andlowering the magnetic shunt 21.

The operation of the above described mechanism to maintain synchronismbetween the conducting disk 12 and the breaks of the line current is asfollows: Assume that the normal condition of the secondary clock is suchthat the cam 52 is in engagement with the tail 51 at the time thecurrent is broken. The latch 39 will be momentarily withdrawn from underthe arm 36, said arm having been lifted slightly by the cam 52, and willreturn to its position shown in the figure before the cam 52 has passedfrom under the tail 51. As long as the secondary clock remains in thiscondition, that is, so long as the shaft 29 remains in synchronism withthe movements of the latch 39 no change will be made in the position ofthe magnetic shunt 21 and the rate of rotation of the disk 12 will beundisturbed. Assume that from some cause the rate of rotation of thedisk 12 is retarded, then when the latch 39 is withdrawn 'by the spring41 as a consequence of the break in the line current the cam 52 will notyet be in engagement with the tail 51 and the arm 36 will drop, thusengaging the spur gear 37 with the segmental gear 32. During saidengagement the shaft 50 will be rotated in a direction to withdraw themagnetic shunt 21 from the poles of the magnets 13 and the rate of thedisk 12 will consequently be accelerated. This acceleration willcontinue, and the shunt 21 will continue to be drawn from the magnet 13until the cam 52 lifts the tail 51, when the arm 36 will be retained bythe latch 39. If the acceleration just given the secondary clock is notsufiicient to bring it into synchronism, at the next operation of thelatch 39, the cam 52 will still be behind the tail 51 and the operationwill be repeated. This shifting of the shunt 21 will continue until theshaft 29 is in synchronism with. the movements of the latch 39, whichfact will be determined by the cam 52 being in engagement with the tail51 at the time of motion of the latch 39.

In the event of the shaft 29 being ahead of the motion of the latch 39,that is, in the event of the conducting disk 12 running fast, the cam 52will have passed the tail 51, when the latch 39 is operated. In thisevent the gear 38 will be engaged by the segmental gear 33 and turneduntil either the cam 53 or the cam 54 relatches the arm 36. Since thegear 35 will be turned in the reverse direction by the action of thegear 38, the magnetic shunt 21 will be approached to the poles of themagnet 13, and the rate of revolution of the conducting disk 12 will bediminished. This action will continue until the shaft 29 is brought intosynchronism with the motion of the shaft, which fact will be determinedby the contact of the cam 52 with the tail 51 at the time the latch 39is operated.

It will be noticed that when the shaft 29 is corrected on account of itsbeing slow, the correction is proportional to the error, that is, themore the shaft 29 is behind the motion of the latch 39, the greater willbe the time during which the gear 32 will act on the gear 37. On theother hand, if the shaft 29 is fast. the correction will be inverselyproportional to the error, that is, a small error will result in a largecorrection. This fact is not material since the action of the gear 38will be to at once retard the disk more than the necessary amount, whichwill throw it to running slow, when the gear 37 will immediately startto correct the error and bring the shaft 29 again into synchronism.However, for the purpose of bringing the shaft 29 into synchronism whenthe shaft is but slightly fast, I have provided the auxiliary cam 53,which is a small angular distance behind the cam 52 and in the event ofthe disk 29 being but slightly fast the resulting correction will be butsmall.

It is obvious that the above described mechanism will always keep thedisk 29 in wires. It is evident that any desired number of clocks havingmechanism like the mechanism of my secondary clock just de scribed maybe driven and controlled from the same line wires. The number of clockswhich can be controlled in this way is simply a question of the currentcarrying capacity of the contacts 18 and 20, and these may be made tohandle a current of any required size.

In some cases it may not be advantageous to allow the usual voltage of110 volts to be on the clock lines, in which event all that is necessaryis to provide a suitable transformer 57 between the break 20 and theline wires to reduce the current to any desired voltage.

My herein described system is very well suited for that class of timecontrol which requires a considerable amount of power at the secondaryclocks. Instances of this will be found in tower clocks where the handsare very large and are exposed to the snow and ice and hence require acomparatively large amount of power to move them. Another field in whichmy improved system can be used to advantage is in various systems oftime stamps and workmens time recorders. In these installations, inaddition to the usual clock hands the motive power is required to moveprinting apparatus of various kinds. Instead of having the entire loadof moving this apparatus thrown on the secondary clock once each minute,I employ a continuously moving motor which is supplied with sufiicientpower to overcome the heaviest load and provide means for synchronizingthis motor and thus run it in unison with the currents sent out over thesystem from the master clock.

Another place in which my herein described system may be used toadvantage is in running program clocks, that is, clocks which arerequired to ring electric bells at predetermined intervals. Inasmuch asmy secondary clocks are in continuous motion as distinguished from theintermittent motions of secondary clocks of other systems, it is veryeasy to arrange the different contacts which are required to closethevbell ringing circuits.

It is obvious that the magnets 45 and 46, instead of being included inthe circuit which furnishes the power to run the secondary clock motormight be included in a separate circuit and the power to run the motorsin the various secondary clocks be taken directly from the light mains.

In Fig. 2 I have shown a circuit embodying this proposed modification.Reference to this figure will show that the magnet 13 is, as before,connected between the line wires 14 and 15. The magnet 45 controllingthe latch 39, instead of being connet-ted to the line wires 14 and 15,is in a separate circuit which includes a battery 117 and a contact 120of the relay 11, whose armature 18 is attracted at predeterminedintervals as before. in each of the secondary clocks is actuated at thepredetermined intervals. This arrangement is a somewhat obviousequivalent to the preferred arrangement as disclosed in Fig. 1. However,it may have some advantages in replacing an existing installation inwhich the wires connecting the various secondary clocks are not wellenough insulated to permit the usual electric light current to be placedupon them. The secondary clocks can then be operated directly from thelight mains and synchronized over the existing clock circuit.

Another advantage of my herein described system is that it may be madepractically noiseless, thereby avoiding the objectionable click whichoccurs each minute in the prior art systems of minute jumpers.

lVhile I have described the synchronizing period in my system as aperiod of one minute, it is obvious that a much longer period betweenthe synchronizing currents may be employed. The length ofthesynchronizing period is solely a question of the uniformity of the loadand the current supply.

Many changes and variations may be made from the precise mechanismherein disclosed without departing from the spirit of my invention,since I claim:

1. In a clock system, the combination of a master clock, a secondaryclock, line wires connecting the two, a continuously running motor,means to close the circuit intermittently, and means in said secondaryclock to bringsaid motor into synchronism with said intermittentcurrents.

2. In a clock system, the combination of line wires, means to impress anintermittent current thereon, a secondary clock con nected to said lineWires, a motor in said secondary clock, time-indicating means controlledby said motor and means to bring said motor into synchronism with saidintermittent currents.

3. In. a clock system, the combination of line wires, means to supply analternating current to said line wires, means to break said alternatingcurrent at predetermined intervals, a secondary clock connected to saidline wires, an alternating motor in said secondary clock, and means tobring the rate of revolution of said motor into synchronism with thebreaks in said current.

4. In a clock system, the combination of line wires, means to supply analternating current to said line wires, a master clock, means governedby said master clock to interrupt said alternating current atpredetermined intervals, a secondary clock con- Thus the magnet 45'nected to said line wires, an alternating motor in said secondary clock,and means to bring the rate of revolution of said motor into synchronismwith the breaks in said current.

5. In a clock system, the combination of line Wires, means to impress analternating current thereon, a master clock, means governed by saidmaster clock to interrupt said alternating current at predeterminedintervals, a secondary clock, an induction motor in said secondaryclock, time-indicating means driven by said induction motor and means tobring said inotor into synchronism with the interruptions. in saidalternating current.

6. In a secondary clock, the combination of a continuously runningmotor, time-indicating means driven thereby, means to control the speedof said motor, line wires to which said secondary clock is connected,means to send a periodically recurring current over said line wires, andmeans to shift said speed-controlling means according as the rate ofrotation of said continuously running motor departs from synchronismwith said current interruptions.

7. In a clock system, the combination of line wires, a secondary clock,an induction motor, means for varying the speed of the same,time-indicating means, a gear connection between said induction motorand said time-indicating means, a member in said secondary clockactuated at predetermined intervals by current sent over said linewires, means to control the speed of said inductionmotor, a gearreversing device adapted to be connected to said speedcontrollingdevice, and means for bringing said gear-reversing device into action tobring the rate of revolution of said motor into synchronism with theinterruptions of the current on said line wires.

8. In a secondary clock, the combination of a continuouslyrunning motor,speedgoverning means for said motor, an element actuated atpredetermined intervals, a rotating shaft driven by said motor, a pairof segmental gears on said shaft and rotating therewith, and means forbringing the rate of rotation of said motor into synchronism with themovements of said periodicallyactuated member, said means being actuatedby said segmental gears to control the position of saidspeed-controlling means.

9. In a secondary clock, the combination of a motor, time-indicatingmeans driven by said motor, a speed control for said motor, a rotatingshaft driven by said motor, a pair of segmental gears mounted on saidrotating shaft, a second gear governing the position of saidspeed-controlling means, and means to bring said segmental gearsperiodically into mesh with said second gear.

10. In a secondary clock, the combination of a motor, time-indicatingmeans driven by said motor, a speed control for said motor, a rotatingshaft driven by said motor, a pair of segmental gears mounted on saidrotating shaft, a second gear governing the position of saidspeed-controlling means, means to bring said gears into operativerelation, and means rotating synchronously with said segmental gear todisengage said second gear from said segmental gears when the latterhave reached a certain position.

11. In a secondary clock, the combination of a motor, time-indicatingmeans driven by said motor, a speed control for said motor, a rotatingshaft driven by said motor, a pair of segmental gears mounted on saidrotating shaft, a second gear governing the position of saidspeed-controlling means, means to bring said gears into operativerelation, and means to disengage said second gear from said segmentalgears when the latter have reached a certain position.

12. In a secondary clock, the combination of an induction motor, amagnetic shunt adapted to vary the speed of said motor, a gearcontrolling the position of said magnetic shunt, a periodically-actuatedelement,

and means governed by said periodically actuated element forestablishing an operative relation between said motor and said gearcontrolling the position of said magnetic shunt.

13. In a secondary clock, the combination of a rotating shaft, a gear onsaid rotating shaft, time-indicating means driven by said rotatingshaft, a motor to drive said rotating shaft, a speed control for saidmotor, a periodically-actuated element, and means governed by saidperiodically actuated element for establishing a connection between saidgear on said rotating shaft and said speed-governing means.

14. In a secondary clock, the combination of an alternating currentmotor, timeindicating means driven by said 'motor, a speed control forsaid motor, a rotating shaft driven by said motor, a pair of segmentalgears mounted on said rotating shaft, a second gear governing theposition of said speed-controlling means, means to bring said gears intooperative relation, and means to disengage said second gear from saidsegmental gears when the latter have reached a certain position.

15. In a secondary clock, the combination of a rotating shaft, a gear onsaid rotating shaft, time-indicating means driven by said rotatingshaft, a motor to drive said rotating shaft, a speed control for saidmotor, 'a periodically-actuated element, and means governed by saidperiodically-actuated element for establishing a connection between saidgear on said rotating shaft and said speed governing means when saidmotor gets out of synchronism with said periodicallyactuated element.

In witness whereof I have hereunto subscribed my name.

ARTHUR F. POOLE.

